migration of DNA compared to RNA in TBE-Urea polyacrylamide gels

[Morten Lindow]

Any experienced biochemist out there who can help answer this?

In a denaturing TBE-Urea polyacrylamide gel, does DNA migrate at the 
same speed as RNA?

In other words: Can I use a DNA size marker to get an idea about the 
size of RNA samples? Will the urea denature the DNA-helix and make it 
single stranded?

My RNA is supposed to be only around 20 nt, so cannot use a RNA ladder 
unless I do radiolabelling.

cheers,

Morten
Copenhagen